It is well known in the art to provide certain types of spacecraft with imaging systems. Three axes stabilized geosynchronous orbit meteorological satellites are exemplary of this type of spacecraft. The imaging system can include a CCD camera or other type of imager that provides rows of pixels that make up an image frame.
It is also known that pixels within a satellite camera image can be precisely located in terms of latitude and longitude on a celestial body, such as the earth, that is being imaged. By example, U.S. Pat. No.: 4,688,092, "Satellite Camera Image Navigation", by A. A. Kamel et al. teaches that a ground-based computer generates models of a satellite's orbit and attitude. The orbit model is generated from measurements of stars and landmarks taken by satellite cameras, and by range data taken by a tracking station. The attitude model is based on star measurements taken by the cameras. The measured data is then fit to the models using a walking least squares fit algorithm, and pixel coordinates are then transformed into earth latitude and longitude coordinates, using the orbit and attitude models. Reference may also be had to U.S. Pat. No. 4,746,976, entitled "Star Sightings by Satellite for Image Navigation", by A. A. Kamel et al.
Also of interest is U.S. Pat. No.: 3,715,594, entitled "Space Vehicle System for Determining Earth's Ultraviolet Radiation Limb", by W. A. Drohan et al., wherein a sensor having a radioactive reference graticule is used to detect the earth's ultraviolet (UV) radiation limb. The detected UV radiation limb is employed as an earth-space boundary reference to derive position information for use in a space vehicle navigation control system.